Graphical user interface for detail-in-context presentations

0001This application is a continuation of U.S. patent application Ser. No. 10/137,648, filed May 3, 2002 now U.S. Pat. No. 7,197,719, the disclosure of which is incorporated herein by reference.

0002This application claims priority from Canadian Patent Application No. 2,345,803, filed May 3, 2001, and incorporated herein by reference.

0003The invention relates to the field of computer graphics processing, and more specifically to a graphical user interface (GUI) to a detail-in-context presentation system.

BACKGROUND OF THE INVENTION

0004Display screens are the primary visual display interface to a computer. One problem with these visual display screens is that they are limited in size, thus presenting a challenge to user interface design, particularly when larger amounts of information is to be displayed. This problem is normally referred to as the “screen real estate problem”.

0005Well-known solutions to this problem include panning, zooming, scrolling or combinations thereof. While these solutions are suitable for a large number of visual display applications, these solutions become less effective where the visual information is spatially related, such as maps, newspapers and such like. In this type of information display, panning, zooming and/or scrolling is not as effective as much of the context of the panned, zoomed or scrolled display is hidden.

0006A recent solution to this problem is the application of “detail-in-context” presentation techniques. Detail-in-context is the magnification of a particular region of interest (the “focal region”) in a data presentation while preserving visibility of the surrounding information. This technique has applicability to the display of large surface area media, such as maps, on limited size computer screens such as personal digital assistance (PDA's) and cell phones.

0007In the detail-in-context discourse, differentiation is often made between the terms “representation” and “presentation”. A representation is a formal system, or mapping, for specifying raw information or data that is stored in a computer or data processing system. For example, a digital map of a city is a representation of raw data including street names and the relative geographic location of streets and utilities. Such a representation may be displayed visually on computer screen or printed on paper. On the other hand, a presentation is a spatial organization of a given representation that is appropriate for the task at hand. Thus, a presentation of a representation organizes such things as the point of view and the relative emphasis of different parts or regions of the representation. For example, a digital map of a city may be presented with a region magnified to reveal street names.

0008In general, a detail-in-context presentation may be considered as a distorted view (or distortion) of a portion of the original representation where the distortion is the result of the application of a “lens” like distortion function to the original representation. A detailed review of various detail-in-context presentation techniques such as Elastic Presentation Space (“EPS”) may be found in a publication by Marianne S. T. Carpendale, entitled “A Framework for Elastic Presentation Space” (Burnaby, British Columbia: Simon Fraser University, 1999), and incorporated herein by reference.

0009Development of increasingly powerful computing devices has lead to new possibilities for applications of detail-in-context viewing. At the same time, the demand for user control over the parameters of a detail-in-context lens has increased. Indeed, one shortcoming of current EPS graphics technology and detail-in-context presentation methods is the lack of an effective user friendly graphical user interface (“GUI”) for the control of lens display parameters. Generally, with a GUI, a user interacts with icons and controls in a GUI display by moving a pointing device, such as a mouse, which causes a censor or pointer to be moved on the display. When the pointer is over the displayed icon or control, the user presses a button, such as a mouse button, to invoke one or more operations to be performed by the computer system.

0010A need therefore exists for a GUI to control one or more features of a detail-in-context display system. Consequently, it is an object of the present invention to obviate or mitigate at least some of the above-mentioned disadvantages.

SUMMARY OF THE INVENTION

0011According to one aspect of the invention, a method is provided for displaying a region of interest within visual information on a display screen of a computer, the region of interest including a focal region and a base region. The method includes the steps of: providing means for selecting at least one parameter for transforming at least one of the region of interest, the focal region, and the base region; selecting the parameter using the means for selecting; transforming the visual information in accordance with a predetermined distortion function and the parameter to produce transformed visual information; and, displaying the transformed visual information on the display screen.

0012According to another aspect of the invention, the parameter includes a magnification for the region of interest, a size for the focal region, a size for the base region, a shape for the focal region, a shape for the base region, a location for the base region within the visual information, and a location for the focal region relative to the base region.

0013According to another aspect of the invention, the means for selecting includes bounding rectangle, handle, crosshairs, and slide bar.

0014Advantageously, the method of the invention is implemented using user friendly graphical user interface.

BRIEF DESCRIPTION OF THE DRAWINGS

0015The invention may best be understood by referring to the following description and accompanying drawings which illustrate the invention. In the drawings:

0016<figref idref="DRAWINGS">FIG. 1</figref> is a graphical construction illustrating a 3D perspective viewing frustum in accordance with known elastic presentation space graphics technology;

0017<figref idref="DRAWINGS">FIG. 2</figref> is a cross-sectional view illustrating a presentation in accordance with known elastic presentation space graphics technology;

0018<figref idref="DRAWINGS">FIG. 3</figref> is a block diagram illustrating an exemplary data processing system for implementing an embodiment of the invention;

0019<figref idref="DRAWINGS">FIG. 4</figref> a partial screen capture illustrating a GUI having lens control elements for user interaction with detail-in-context data presentations in accordance with an embodiment of the invention; and,

0020<figref idref="DRAWINGS">FIG. 5</figref> is a flow chart illustrating a general method for displaying a region of interest within visual information on a display screen of a computer in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

0021In the following description, numerous specific details are set forth to provide a thorough understanding of the invention. However, it is understood that the invention may be practiced without these specific details. In other instances, well-known software, circuits, structures and techniques have not been described or shown in detail in order not to obscure the invention. The term “data processing system” is used herein to refer to any machine for processing data, including the computer systems and network arrangements described herein. The term “Elastic Presentation Space” or “EPS” is used herein to refer to techniques that allow for the adjustment of a visual presentation without interfering with the information content of the representation. The adjective “elastic” is included in the term as it implies the capability of stretching and deformation and subsequent return to an original shape. EPS graphics technology is described by Carpendale in <i>A Framework for Elastic Presentation Space </i>(Carpendale, Marianne S. T., <i>A Framework for Elastic Presentation Space </i>(Burnaby, British Columbia: Simon Fraser University, 1999)) which is incorporated herein by reference. In EPS graphics technology, a two-dimensional visual representation is placed onto a surface; this surface is placed in three-dimensional space; the surface, containing the representation, is viewed through perspective projection; and the surface is manipulated to effect the reorganization of image details. The presentation transformation is separated into two steps: surface manipulation or distortion and perspective projection. In the drawings, like numerals refer to like structures or processes.

0022Referring to <figref idref="DRAWINGS">FIG. 1</figref>, there is shown a graphical representation <b>100</b> of the geometry for constructing a three-dimensional (3D) perspective viewing frustum <b>220</b> relative to an x, y, z coordinate system in accordance with known elastic presentation space (“EPS”) graphics technology. In the EPS, detail-in-context views of 2D visual representations are created with sight-line aligned distortions of a two-dimensional (2D) information presentation surface within a 3D perspective viewing frustum <b>220</b>. In EPS, magnification of regions of interest and the accompanying compression of the contextual region to accommodate this change in scale are produced by the movement of regions of the surface towards the viewpoint <b>240</b> located at the apex of the pyramidal shape <b>220</b> containing the frustum. The process of projecting these transformed layouts via a perspective projection results in a new 2D layout which includes the zoomed and compressed regions. The use of the third dimension and perspective distortion to provide magnification in EPS provides a meaningful metaphor for the process of distorting the information presentation surface. The 3D manipulation of the information presentation surface in such a system is an intermediate step in the process of creating a new 2D layout of the information.

0023Referring to <figref idref="DRAWINGS">FIG. 2</figref>, there is shown geometrical representation of a presentation <b>200</b> in accordance with known EPS graphics technology. EPS graphics technology employs viewer-aligned perspective projections to produce detail-in-context presentations in a reference view plane <b>201</b> which may be viewed on a display. Undistorted 2D data points are located in a basal plane <b>210</b> of a 3D perspective viewing volume or frustum <b>220</b> which is defined by extreme rays <b>221</b> and <b>222</b> and the basal plane <b>210</b>. A viewpoint (“VP”) <b>240</b> is located above the centre point of the basal plane <b>210</b> and reference view plane <b>201</b>. Points in the basal plane <b>210</b> are displaced upward onto a distorted surface <b>230</b> which is defined by a general 3D distortion function (i.e. a detail-in-context distortion basis function). The direction of the viewer-aligned perspective projection corresponding to the distorted surface <b>230</b> is indicated by the line FPo-FP <b>231</b> drawn from a point FPo <b>232</b> in the basal plane <b>210</b> through the point FP <b>233</b> which corresponds to the focus or focal region or focal point of the distorted surface <b>230</b>.

0024To reiterate, EPS refers to a collection of know-how and techniques for performing “detail-in-context viewing” (also known as “multi-scale viewing” and “distortion viewing”) of information such as images, maps, and text, using a projection technique summarized below. EPS is applicable to multidimensional data and is well suited to implementation on a computer for dynamic detail-in-context display on an electronic display surface such as a monitor. In the case of two dimensional data, EPS is typically characterized by magnification of areas of an image where detail is desired, in combination with compression of a restricted range of areas of the remaining information (the “context”), the end result typically giving the appearance of a lens having been applied to the display surface. EPS has numerous advantages over conventional zoom, pan, and scroll technologies, including the capability of preserving the visibility of information outside the local region of interest.

0025In general, in EPS, the source image to be viewed is located in the basal plane. Magnification and compression are achieved through elevating elements of the source image relative to the basal plane, and then projecting the resultant distorted surface onto the reference view plane. EPS performs detail-in-context presentation of n-dimensional data through the use of a procedure wherein the data is mapped into a region in an (n+1) dimensional space, manipulated through perspective projections in the (n+1) dimensional space, and then finally transformed back into n-dimensional space for presentation.

0026For example, and referring to <figref idref="DRAWINGS">FIGS. 1 and 2</figref>, in two dimensions, EPS can be implemented through the projection of an image onto a reference plane <b>201</b> in the following manner. The source image is located on a basal plane <b>210</b>, and those regions of interest <b>233</b> of the image for which magnification is desired are elevated so as to move them closer to a reference plane situated between the reference viewpoint <b>240</b> and the reference view plane (RVP) <b>201</b>. Magnification of the “focal region” <b>233</b> closest to the RVP varies inversely with distance from the RVP <b>201</b>. As shown in <figref idref="DRAWINGS">FIGS. 1 and 2</figref>, compression of regions outside the focal region <b>233</b> is a function of both distance from the RVP <b>201</b>, and the gradient of the function describing the vertical distance from the RVP <b>201</b> with respect to horizontal distance from the focal region <b>233</b>. The resultant combination of magnification and compression of the image as seen from the reference viewpoint <b>240</b> results in a lens-like effect similar to that of a magnifying glass applied to the image, and the resultant distorted image may be referred to as a “pliable display surface”. Hence, the various functions used to vary the magnification and compression of the image via vertical displacement from the basal plane <b>210</b> are described as lenses, lens types, or lens functions. Lens functions that describe basic lens types with point and circular focal regions, as well as certain more complex lenses and advanced capabilities such as folding, have previously been described by Carpendale.

0027System. Referring to <figref idref="DRAWINGS">FIG. 3</figref>, there is shown a block diagram of an exemplary data processing system <b>300</b> for implementing an embodiment of the invention. The data processing system is suitable for implementing EPS technology in conjunction with a graphical user interface (“GUI”). The data processing system <b>300</b> includes an input device <b>310</b>, a central processing unit or CPU <b>320</b>, memory <b>330</b>, and a display <b>340</b>. The input device <b>310</b> may be a keyboard, mouse, trackball, or similar device. The CPU <b>320</b> may include dedicated coprocessors and memory devices. The memory <b>330</b> may include RAM, ROM, databases, or disk devices. And, the display <b>340</b> may include a computer screen or terminal device. The data processing system <b>300</b> has stored therein data representing sequences of instructions which when executed cause the method described herein to be performed. Of course, the data processing system <b>300</b> may contain additional software and hardware a description of which is not necessary for understanding the invention.

0028GUI with Lens Control Elements. As mentioned, detail-in-context presentations of data using techniques such as pliable surfaces, as described by Carpendale, are useful in presenting large amounts of information on limited-size display surfaces. Detail-in-context views allow magnification of a particular region of interest (the “focal region”) <b>233</b> in a data presentation while preserving visibility of the surrounding information <b>210</b>. In the following, a GUI having lens control elements that can be implemented in software and applied to the control of detail-in-context data presentations, including EPS and pliable surfaces, is described. The software can be loaded into and run by the exemplary data processing system <b>300</b> of <figref idref="DRAWINGS">FIG. 3</figref>.

0029Referring to <figref idref="DRAWINGS">FIG. 4</figref>, there is a partial screen capture illustrating a GUI <b>400</b> having lens control elements for user interaction with detail-in-context data presentations in accordance with an embodiment of the invention. Detail-in-context data presentations are characterized by magnification of areas of an image where detail is desired, in combination with compression of a restricted range of areas of the remaining information (i.e. the “context”), the end result typically giving the appearance of a “lens” having been applied to the display screen surface. This “lens” <b>410</b> includes a “focal region” <b>420</b> having high magnification, a surrounding “shoulder region” <b>430</b> where information is typically visibly compressed, and a “base” <b>412</b> surrounding the shoulder region <b>430</b> and defining the extent of the lens <b>410</b>. In <figref idref="DRAWINGS">FIG. 4</figref>, the lens <b>410</b> is shown with a circular shaped base <b>412</b> (or outline) and with a focal region <b>420</b> lying near the center of the lens <b>410</b>. However, the lens <b>410</b> and focal region <b>420</b> may have any desired shape. Referring again to <figref idref="DRAWINGS">FIG. 2</figref>, the lens <b>410</b> corresponds to the projection of the distorted surface <b>230</b> and focal region <b>233</b> onto the reference plane <b>201</b>.

0030In general, the GUI <b>400</b> has lens control elements that, in combination, provide for the interactive control of the lens <b>410</b>. The effective control of the characteristics of the lens <b>410</b> by a user (i.e. dynamic interaction with a detail-in-context lens) is advantageous. At any given time, one or more of these lens control elements may be made visible to the user on the display surface <b>340</b> by appearing as overlay icons on the lens <b>410</b>. Interaction with each element is performed via the motion of a pointing device <b>310</b> (e.g. mouse), with the motion resulting in an appropriate change in the corresponding lens characteristic. As will be described, selection of which lens control element is actively controlled by the motion of the pointing device <b>310</b> at any given time is determined by the proximity of the icon representing the pointing device <b>310</b> on the display surface <b>340</b> (e.g. cursor) to the appropriate component of the lens <b>410</b>. For example, “dragging” of the pointing device at the periphery of the bounding rectangle of the lens base <b>412</b> causes a corresponding change in the size of the lens <b>410</b> (i.e. “resizing”). Thus, the GUI <b>400</b> provides the user with a visual representation of which lens control element is being adjusted through the display of one or more corresponding icons.

0031For ease of understanding, the following discussion will be in the context of using a two-dimensional pointing device <b>310</b> that is a mouse, but it will be understood that the invention may be practiced with other 2-D or 3-D (or even greater numbers of dimensions) pointing devices including a trackball and keyboard.

0032A mouse <b>310</b> controls the position of a cursor icon <b>401</b> that is displayed on the display screen <b>340</b>. The cursor <b>401</b> is moved by moving the mouse <b>310</b> over a flat surface, such as the top of a desk, in the desired direction of movement of the cursor <b>401</b>. Thus, the two-dimensional movement of the mouse <b>310</b> on the flat surface translates into a corresponding two-dimensional movement of the cursor <b>401</b> on the display screen <b>340</b>.

0033A mouse <b>310</b> typically has one or more finger actuated control buttons (i.e. mouse buttons). While the mouse buttons can be used for different functions such as selecting a menu option pointed at by the cursor <b>401</b>, the disclosed invention may use a single mouse button to “select” a lens <b>410</b> and to trace the movement of the cursor <b>401</b> along a desired path. Specifically, to select a lens <b>410</b>, the cursor <b>401</b> is first located within the extent of the lens <b>410</b>. In other words, the cursor <b>401</b> is “pointed” at the lens <b>410</b>. Next, the mouse button is depressed and released. That is, the mouse button is “clicked”. Selection is thus a point and click operation. To trace the movement of the cursor <b>401</b>, the cursor <b>401</b> is located at the desired starting location, the mouse button is depressed to signal the computer <b>320</b> to activate a lens control element, and the mouse <b>310</b> is moved while maintaining the button depressed. After the desired path has been traced, the mouse button is released. This procedure is often referred to as “clicking” and “dragging” (i.e. a click and drag operation). It will be understood that a predetermined key on a keyboard <b>310</b> could also be used to activate a mouse click or drag. In the following, the term “clicking” will refer to the depression of a mouse button indicating a selection by the user and the term “dragging” will refer to the subsequent motion of the mouse <b>310</b> and cursor <b>401</b> without the release of the mouse button.

0034The GUI <b>400</b> may include the following lens control elements: move, pickup, resize base, resize focus, fold, and magnify. Each of these lens control elements has at least one lens control icon or alternate cursor icon associated with it. In general, when a lens <b>410</b> is selected by a user through a point and click operation, the following lens control icons may be displayed over the lens <b>410</b>: pickup icon <b>450</b>, base outline icon <b>412</b>, base bounding rectangle icon <b>411</b>, focal region bounding rectangle icon <b>421</b>, handle icons <b>481</b>, <b>482</b>, <b>491</b>, and magnify slide bar icon <b>440</b>. Typically, these icons are displayed simultaneously after selection of the lens <b>410</b>. In addition, when the cursor <b>401</b> is located within the extent of a selected lens <b>410</b>, an alternate cursor icon <b>460</b>, <b>470</b>, <b>480</b>, <b>490</b> may be displayed over the lens <b>410</b> to replace the cursor <b>401</b> or may be displayed in combination with the cursor <b>401</b>. These lens control elements, corresponding icons, and their effects on the characteristics of a lens <b>410</b> are described below with reference to <figref idref="DRAWINGS">FIG. 4</figref>.

0035In general, when a lens <b>410</b> is selected by a point and click operation, bounding rectangle icons <b>411</b>, <b>421</b> are displayed surrounding the base <b>412</b> and focal region <b>420</b> of the selected lens <b>410</b> to indicate that the lens <b>410</b> has been selected. With respect to the bounding rectangles <b>411</b>, <b>421</b> one might view them as glass windows enclosing the lens base <b>412</b> and focal region <b>420</b>, respectively. The bounding rectangles <b>411</b>, <b>421</b> include handle icons <b>481</b>, <b>482</b>, <b>491</b> allowing for direct manipulation of the enclosed base <b>412</b> and focal region <b>420</b> as will be explained below. Thus, the bounding rectangles <b>411</b>, <b>421</b> not only inform the user that the lens <b>410</b> has been selected, but also provide the user with indications as to what manipulation operations might be possible for the selected lens <b>410</b> though use of the displayed handles <b>481</b>, <b>482</b>, <b>491</b>. Note that it is well within the scope of the present invention to provide a bounding region having a shape other than generally rectangular. Such a bounding region could be of any of a great number of shapes including oblong, oval, ovoid, conical, cubic, cylindrical, polyhedral, spherical, etc.

0036Moreover, the cursor <b>401</b> provides a visual cue indicating the nature of an available lens control element. As such, the cursor <b>401</b> will generally change in form by simply pointing to a different lens control icon <b>450</b>, <b>412</b>, <b>411</b>, <b>421</b>, <b>481</b>, <b>482</b>, <b>491</b>, <b>440</b>. For example, when resizing the base <b>412</b> of a lens <b>410</b> using a corner handle <b>491</b>, the cursor <b>401</b> will change form to a resize icon <b>490</b> once it is pointed at (i.e. positioned over) the corner handle <b>491</b>. The cursor <b>401</b> will remain in the form of the resize icon <b>490</b> until the cursor <b>401</b> has been moved away from the corner handle <b>491</b>.

0037Move. Lateral movement of a lens <b>410</b> is provided by the move lens control element of the GUI. This functionality is accomplished by the user first selecting the lens <b>410</b> through a point and click operation. Then, the user points to a point within the lens <b>410</b> that is other than a point lying on a lens control icon <b>450</b>, <b>412</b>, <b>411</b>, <b>421</b>, <b>481</b>, <b>482</b>, <b>491</b>, <b>440</b>. When the cursor <b>401</b> is so located, a move icon <b>460</b> is displayed over the lens <b>410</b> to replace the cursor <b>401</b> or may be displayed in combination with the cursor <b>401</b>. The move icon <b>460</b> not only informs the user that the lens <b>410</b> may be moved, but also provides the user with indications as to what movement operations are possible for the selected lens <b>410</b>. For example, the move icon <b>460</b> may include arrowheads indicating up, down, left, and right motion. Next, the lens <b>410</b> is moved by a click and drag operation in which the user clicks and drags the lens <b>410</b> to the desired position on the screen <b>340</b> and then releases the mouse button <b>310</b>. The lens <b>410</b> is locked in its new position until a further pickup and move operation is performed.

0038Pickup. Lateral movement of a lens <b>410</b> is also provided by the pickup lens control element of the GUI. This functionality is accomplished by the user first selecting the lens <b>410</b> through a point and click operation. As mentioned above, when the lens <b>410</b> is selected a pickup icon <b>450</b> is displayed over the lens <b>410</b> near the centre of the lens <b>410</b>. Typically, the pickup icon <b>450</b> will be a crosshairs. In addition, a base outline <b>412</b> is displayed over the lens <b>410</b> representing the base <b>412</b> of the lens <b>410</b>. The crosshairs <b>450</b> and lens outline <b>412</b> not only inform the user that the lens has been selected, but also provides the user with an indication as to the pickup operation that is possible for the selected lens <b>410</b>. Next, the user points at the crosshairs <b>450</b> with the cursor <b>401</b>. Then, the lens outline <b>412</b> is moved by a click and drag operation in which the user clicks and drags the crosshairs <b>450</b> to the desired position on the screen <b>340</b> and then releases the mouse button <b>310</b>. The full lens <b>410</b> is then moved to the new position and is locked there until a further pickup operation is performed. In contrast to the move operation described above, with the pickup operation, it is the outline <b>412</b> of the lens <b>410</b> that the user repositions rather than the full lens <b>410</b>.

0039Resize Base. Resizing of the base <b>412</b> (or outline) of a lens <b>410</b> is provided by the resize base lens control element of the GUI. After the lens <b>410</b> is selected, a bounding rectangle icon <b>411</b> is displayed surrounding the base <b>412</b>. The bounding rectangle <b>411</b> includes handles <b>491</b>. These handles <b>491</b> can be used to stretch the base <b>412</b> taller or shorter, wider or narrower, or proportionally larger or smaller. The corner handles <b>491</b> will keep the proportions the same while changing the size. The middle handles (not shown) will make the base <b>412</b> taller or shorter, wider or narrower. Resizing the base <b>412</b> by the corner handles <b>491</b> will keep the base <b>412</b> in proportion. Resizing the base <b>412</b> by the middle handles (not shown) will change the proportions of the base <b>412</b>. That is, the middle handles (not shown) change the aspect ratio of the base <b>412</b> (i.e. the ratio between the height and the width of the bounding rectangle <b>411</b> of the base <b>412</b>). When a user points at a handle <b>491</b> with the cursor <b>401</b> a resize icon <b>490</b> may be displayed over the handle <b>491</b> to replace the cursor <b>401</b> or may be displayed in combination with the cursor <b>401</b>. The resize icon <b>490</b> not only informs the user that the handle <b>491</b> may be selected, but also provides the user with indications as to the resizing operations that are possible with the selected handle. For example, the resize icon <b>490</b> for a corner handle <b>491</b> may include arrows indicating proportional resizing. The resize icon (not shown) for a middle handle (not shown) may include arrows indicating width resizing or height resizing. After pointing at the desired handle <b>491</b>, the user would click and drag the handle <b>491</b> until the desired shape and size for the base <b>412</b> is reached. Once the desired shape and size are reached, the user would release the mouse button <b>310</b>. The base <b>412</b> of the lens <b>410</b> is then locked in its new size and shape until a further base resize operation is performed.

0040Resize Focus. Resizing of the focal region <b>420</b> of a lens <b>410</b> is provided by the resize focus lens control element of the GUI. After the lens <b>410</b> is selected, a bounding rectangle icon <b>421</b> is displayed surrounding the focal region <b>420</b>. The bounding rectangle <b>421</b> includes handles <b>481</b>, <b>482</b>. These handles <b>481</b>, <b>482</b> can be used to stretch the focal region <b>420</b> taller or shorter, wider or narrower, or proportionally larger or smaller. The corner handles <b>481</b> will keep the proportions the same while changing the size. The middle handles <b>482</b> will make the focal region <b>420</b> taller or shorter, wider or narrower. Resizing the focal region <b>420</b> by the corner handles <b>481</b> will keep the focal region <b>420</b> in proportion. Resizing the focal region <b>420</b> by the middle handles <b>482</b> will change the proportions of the focal region <b>420</b>. That is, the middle handles <b>482</b> change the aspect ratio of the focal region <b>420</b> (i.e. the ratio between the height and the width of the bounding rectangle <b>421</b> of the focal region <b>420</b>). When a user points at a handle <b>481</b>, <b>482</b> with the cursor <b>401</b> a resize icon <b>480</b> may be displayed over the handle <b>481</b>, <b>482</b> to replace the cursor <b>401</b> or may be displayed in combination with the cursor <b>401</b>. The resize icon <b>480</b> not only informs the user that a handle <b>481</b>, <b>482</b> may be selected, but also provides the user with indications as to the resizing operations that are possible with the selected handle. For example, the resize icon <b>480</b> for a corner handle <b>481</b> may include arrows indicating proportional resizing. The resize icon <b>480</b> for a middle handle <b>482</b> may include arrows indicating width resizing or height resizing. After pointing at the desired handle <b>481</b>, <b>482</b>, the user would click and drag the handle <b>481</b>, <b>482</b> until the desired shape and size for the focal region <b>420</b> is reached. Once the desired shape and size are reached, the user would release the mouse button <b>310</b>. The focal region <b>420</b> is then locked in its new size and shape until a further focus resize operation is performed.

0041Fold. Folding of the focal region <b>420</b> of a lens <b>410</b> is provided by the fold control element of the GUI. In general, control of the degree and direction of folding (i.e. skewing of the viewer aligned vector <b>231</b> as described by Carpendale) is accomplished by a click and drag operation on a point <b>471</b>, other than a handle <b>481</b>, <b>482</b>, on the bounding rectangle <b>421</b> surrounding the focal region <b>420</b>. The direction of folding is determined by the direction in which the point <b>471</b> is dragged. The degree of folding is determined by the magnitude of the translation of the cursor <b>401</b> during the drag. In general, the direction and degree of folding corresponds to the relative displacement of the focus <b>420</b> with respect to the lens base <b>410</b>. In other words, and referring to <figref idref="DRAWINGS">FIG. 2</figref>, the direction and degree of folding corresponds to the displacement of the point FP <b>233</b> relative to the point FPo <b>232</b>, where the vector joining the points FPo <b>232</b> and FP <b>233</b> defines the viewer aligned vector <b>231</b>.

0042In particular, after the lens <b>410</b> is selected, a bounding rectangle icon <b>421</b> is displayed surrounding the focal region <b>420</b>. The bounding rectangle <b>421</b> includes handles <b>481</b>, <b>482</b>. When a user points at a point <b>471</b>, other than a handle <b>481</b>, <b>482</b>, on the bounding rectangle <b>421</b> surrounding the focal region <b>420</b> with the cursor <b>401</b>, a fold icon <b>470</b> may be displayed over the point <b>471</b> to replace the cursor <b>401</b> or may be displayed in combination with the cursor <b>401</b>. The fold icon <b>470</b> not only informs the user that a point <b>471</b> on the bounding rectangle <b>421</b> may be selected, but also provides the user with indications as to what fold operations are possible. For example, the fold icon <b>470</b> may include arrowheads indicating up, down, left, and right motion. By choosing a point <b>471</b>, other than a handle <b>481</b>, <b>482</b>, on the bounding rectangle <b>421</b> a user may control the degree and direction of folding. To control the direction of folding, the user would click on the point <b>471</b> and drag in the desired direction of folding. To control the degree of folding, the user would drag to a greater or lesser degree in the desired direction of folding. Once the desired direction and degree of folding is reached, the user would release the mouse button <b>310</b>. The lens <b>410</b> is then locked with the selected fold until a further fold operation is performed.

0043Magnify. Magnification of the lens <b>410</b> is provided by the magnify lens control element of the GUI. After the lens <b>410</b> is selected, the magnify control is presented to the user as a slide bar icon <b>440</b> near or adjacent to the lens <b>410</b> and typically to one side of the lens <b>410</b>. Sliding the bar <b>441</b> of the slide bar <b>440</b> results in a proportional change in the magnification of the lens <b>410</b>. The slide bar <b>440</b> not only informs the user that magnification of the lens <b>410</b> may be selected, but also provides the user with an indication as to what level of magnification is possible. The slide bar <b>440</b> includes a bar <b>441</b> that may be slid up and down, or left and right, to adjust and indicate the level of magnification. To control the level of magnification, the user would click on the bar <b>441</b> of the slide bar <b>440</b> and drag in the direction of desired magnification level. Once the desired level of magnification is reached, the user would release the mouse button <b>310</b>. The lens <b>410</b> is then locked with the selected magnification until a further magnification operation is performed.

0044Typically, the focal region <b>420</b> is an area of the lens <b>410</b> having constant magnification (i.e. if the focal region is a plane). Again referring to <figref idref="DRAWINGS">FIGS. 1 and 2</figref>, magnification of the focal region <b>420</b>, <b>233</b> varies inversely with the distance from the focal region <b>420</b>, <b>233</b> to the reference view plane (RVP) <b>201</b>. Magnification of areas lying in the shoulder region <b>430</b> of the lens <b>410</b> also varies inversely with their distance from the RVP <b>201</b>. Thus, magnification of areas lying in the shoulder region <b>430</b> will range from unity at the base <b>412</b> to the level of magnification of the focal region <b>420</b>.

0045Icon Hiding. Advantageously, a user may choose to hide one or more lens control icons <b>450</b>, <b>412</b>, <b>411</b>, <b>421</b>, <b>481</b>, <b>482</b>, <b>491</b>, <b>440</b> shown in <figref idref="DRAWINGS">FIG. 4</figref> from view so as not to impede the user's view of the data (i.e. visual information) within the lens <b>410</b>. This may be helpful, for example, during a move operation. A user may select this option through means such as a menu or lens property dialog box.

0046Method. Referring to <figref idref="DRAWINGS">FIG. 5</figref>, there is shown a flow chart <b>500</b> illustrating a general method for displaying a region of interest within visual information on a display screen of a computer, the region of interest having a focal region and a base region, in accordance with an embodiment of the invention. At step <b>501</b>, the method starts. At step <b>502</b>, means are provided for choosing at least one parameter for transforming at least one of the region of interest, the focal region, and the base region. At step <b>503</b>, the parameter is selected using the selecting means. At step <b>504</b>, the visual information is transformed in accordance with a predetermined distortion function and the parameter to produce transformed visual information. At step <b>505</b>, the transformed visual information is displayed on the display screen. At step <b>506</b>, the method ends. The selected parameter may include a magnification for the region of interest <b>410</b>, a size for the focal region <b>420</b>, a size for the base region <b>410</b>, a shape for the focal region <b>420</b>, a shape for the base region <b>410</b>, a location for the base region within the visual information <b>450</b>, <b>460</b>, and a location for the focal region relative to the base region <b>470</b>. The means for selecting includes slide bars <b>440</b> and handles <b>481</b>, <b>482</b>, <b>491</b>, <b>471</b>, <b>441</b>.

0047Data Carrier Product. The sequences of instructions which when executed cause the method described herein to be performed by the exemplary data processing system of <figref idref="DRAWINGS">FIG. 3</figref> can be contained in a data carrier product according to one embodiment of the invention. This data carrier product can be loaded into and run by the exemplary data processing system of <figref idref="DRAWINGS">FIG. 3</figref>.

0048Computer Software Product. The sequences of instructions which when executed cause the method described herein to be performed by the exemplary data processing system of <figref idref="DRAWINGS">FIG. 3</figref> can be contained in a computer software product according to one embodiment of the invention. This computer software product can be loaded into and run by the exemplary data processing system of <figref idref="DRAWINGS">FIG. 3</figref>.

0049Integrated Circuit Product. The sequences of instructions which when executed cause the method described herein to be performed by the exemplary data processing system of <figref idref="DRAWINGS">FIG. 3</figref> can be contained in an integrated circuit product including a coprocessor or memory according to one embodiment of the invention. This integrated circuit product can be installed in the exemplary data processing system of <figref idref="DRAWINGS">FIG. 3</figref>.

0050Although the invention has been described with reference to certain specific embodiments, various modifications thereof will be apparent to those skilled in the art without departing from the spirit and scope of the invention as outlined in the claims appended hereto.